Traction drive fluid that is used for traction drive lubricating oil for driving a traction drive apparatus for stepless regulators in automobiles and industrial machines is required to have specific properties of high traction coefficient and low pour point. To meet the requirement, cyclic compound derivatives are used in base oil of traction drive fluid. For example, dimers of bicyclo[2.2.1]heptane derivatives have been proposed (Japanese Patent No. 2,060,214).
Therefore, bicyclo[2.2.1]heptane derivatives, especially 2-methylene-3-methylbicyclo[2.2.1]heptane, 2,3-dimethylbicyclo[2.2.1]hept-2-ene, 2-ethylidenebicyclo[2.2.1]heptane and 2-ethylbicyclo[2.2.1]-hept-2-ene are important compounds as materials for producing base oil of traction drive fluid.
Heretofore, the compounds of the type are obtained, for example, by reacting crotonaldehyde with dicyclopentadiene through Diels-Alder reaction, then hydrogenating the reaction product and dehydrating it. The process of producing bicyclo[2.2.1] compounds requires three steps of Diels-Alder reaction, hydrogenation and dehydration. Another problem with the process is that the reactant crotonaldehyde is relatively expensive and therefore the production costs are high.
Accordingly, it is desired to develop more economical and efficient novel methods of producing bicyclo[2.2.1]heptane derivatives.
The present invention has been made in consideration of the above-mentioned point, and its object is to provide economical and efficient methods for producing bicyclo[2.2.1]heptane derivatives such as 2-methylene-3-methylbicyclo[2.2.1]heptane, 2,3-dimethylbicyclo[2.2.1]hept-2-ene, 2-ethylidenebicyclo[2.2.1]heptane and 2-ethylbicyclo[2.2.1]-hept-2-ene.